Just in case I need to reset the computer, is there step by step instruction on how to do so? I know my other car you need to unplug the cables from the battery for awhile to reset and my MB I need to put the key in position 2, leave the gas pedal down for 5 seconds, turn the key back to position 0,release the gas pedaland leave the key in for 2 minutes.

 

Yeah to do a hard reset, you would disconnect battery negative for at least 5 minutes. Remember to programme windows when you are done.
This will not however clear out codes stored in the ECM.

 

Thanks JaguarFactoryTech....you've been very helpful.[sm=smiley20.gif]

 

hi, I also have an 08 XKR. Will resetting the ECU clear the check engine light?Once in a whileI get the check fuel filler cap sign on and then it goes away followed by the check engine light. When I take it to the dealer they turn it back off but it's a pain to go wait at the dealer. Can this be handled by just unplugging and replugging the battery?

thanks in advance.

 

Nope, unplugging the battery does not clear codes/check engine lights....

 

CORRECT WHT, AND TO DO A HARD REBOOT YOU HAVE TO DISCHARGE THE CAPACITORS IN THE ECU(ALL ECUS) AND TO CORRECTLY DISCHARGE A CAPACITOR WHICH IS NOTHING MORE THAN A BATTERY YOU HAVE TO GIVE IT A PATH TO GROUND. TO DO THAT DISCONNECT THE NEGATIVE BATTERY TERMINAL FROM THE BATTERY AND MOMENTARILY TOUCH IT TO THE STILL CONNECTED POSITIVE, THIS GIVES ALL THE CAPACITORS A PATH TO GROUND AND WITH ERASES ALL VOLATILE MEMORY.(CK ENGINE LIGHT CODES ARE STORED IN NONVOLATILE SO THEY NO LONGER ERASE THIS WAY)SOMEBODY(JIM?) STICKY THIS SO IT DOESNT HAVE TO BE RETYPED ALL THE TIME(2ND TIME TODAY) AND YES LIKE FACTOTECH SAID, RESET, WINDOWS, CLOCK, SUNROOF, RADIO(MAKE SURE YOU HAVE CODE FIRST IF YOU HAVE AN ANTITHEFT UNIT) AND YOUR DONE. TO RESET CODES AND NOT GO TO THE DEALER, GO TO NEIGHBORHOOD AUTOPARTS STORE, MOST HAVE GENERIC SCANNERS THAT CAN TAKE CARE OF ALOT OF CODES THAT COMEUP, JUST WRITE EM DONE SO IF THEY RETURN YOU KNOW THE CAR IS CONTINUING TO SEE THE SAME PROBLEM

 

Well put brutal.. [sm=closed.gif]

 

suprise suprise... last night I took the car out for a spin... no check engine light! wtf? fuel filler cap light turned off too. in any case, thanks BRUTAL for all of the great info. I saved it on my comp. so I don't have to look it up again. you da man~~~

 

Hi, did I read correctly (positive and negative?) and do this also work for a S-type?:

DISCONNECT THE NEGATIVE BATTERY TERMINAL FROM THE BATTERY AND MOMENTARILY TOUCH IT TO THE STILL CONNECTED POSITIVE

 

Hello Sir,
can you please give me a brief summary of how to reset these items?

Thank you very much.

<<<Mathew>>>

 

I have a problem with a random 'Restricted Performance' warning. It usually happens when I go over a bump.

I want to reset the ECUs but BRUTAL's suggestion of touching the negative terminal to the positive sounds extremely foolish and, anyway, mine won't reach and there must be a good reason for this.

Does anyone know any sensible way to reset the ECUs?

 

@John Duffy-Why do you think Brutal's suggestion sounds "extremely foolish"?

 

Mr Duffy: placing two electrical points at the same level of potential in a closed loop simply gives a completed neutral potential circuit. This will give the capacitors a completed circuit in which to discharge.

 

I am no electrician, but, if the positive terminal is still connected to the battery then how do you get a 'neutral' potential circuit. I could understand it if the positive terminal was not connected.

 

To the person who said 'We didn't leave the stone age because we ran out of rocks...' I would like to say the following:- I purchased my first Jaguar in 1972, a 420, followed by an XJ6, an XJ12, an XJ 4.2C, then five new XJS V12s, two XJS 4.0 (one convertible), and three XK8 convertibles and an XK150 3.8s DHC (genuine with matching numbers). From the first XJS until now, they were all new vehicles (except the 150). I retired to Antigua five years ago and a year ago decided to buy an old XK8 convertible and import it to Antigua. Import duties double the cost and there is no Jaguar agent in Antigua hence the older car.

My first XK8 had a battery failure and the garage connected the new battery the wrong way round and it blew all the instrument package. Fortunately, Jaguar paid GB£2,500. I probably know more about Jaguars than most people and I have never heard of anyone suggesting you connect the negative terminal, albeit temporarily, to the positive side whilst it is connected to the battery. I do wonder what Jaguar would say to this suggestion particularly in these days of sensitive electronics.

 

My board name is rscultho...

Firstly, let's make sure we're on the same page. The original poster (BRUTAL) did not state to connect the positive and negative terminals of the battery together. This would be stupid.

Connecting both ends of a piece of wire to a positive terminal does not create a difference in potential. They are both touching the same terminal. There is no path for current to flow.

So if I take a battery, and take a piece of wire, and touch both ends of the wire to the positive terminal of the battery (NOTHING SHOULD BE TOUCHING THE NEGATIVE TERMINAL) absolutely nothing will happen.

As to the rest of your post, I am not sure what you are trying to say. Nobody impugned any of your knowledge or your ability. I've owned quite a few cars, some bought new off the lot as well - for whatever that's worth. Are you touting your wealth or age or something?

I also have a degree in computer engineering with a minor in electrical engineering. I have designed a microprocessor in my time complete with its own unique control store, and I have a patent on a 70 Million dollar software system in use by a major airline.

IS THAT ALL YOU GOT????!!!!

 

BTW, you've owned a lot of nice cars...and please note my smiley face in my previous post...

 

I did a hard reset last night and got my car to start. However I have a check engine light plus low coolant and low oil pressure lights. Will these eventually go away or do I get to go see the dealer? Thanks, Barry

 

There's a lot of code readers out there and was wondering which one is in expensive and great to use? I heard there is one you can use on your iphone now...some sort of app I guess that goes with it. Any ideas?
Thanks!